After losing Peyton Manning to retirement and Brock Osweiler to the Houston Texans in free agency, the Denver Broncos now face the possibility of entering next season without Pro Bowl running back C.J. Anderson.

Anderson, a restricted free agent, signed a four-year, $18 million offer sheet with the Miami Dolphins on Thursday, a league source told ESPN’s Adam Schefter. The Broncos have five days to match the offer sheet, which reportedly includes $10 million guaranteed, or let the 25-year-old walk away.

In a somewhat surprising move, the Broncos placed a low-round tender worth $1.671 million on Anderson, who rushed for 720 yards and five touchdowns last season. The designation means that although the Broncos can match the Dolphins’ offer, they also won’t receive compensation if they let Anderson sign with Miami, since the running back entered the NFL as an undrafted free agent. In contrast, the Broncos could have guaranteed themselves compensation in the event of an exit by giving Anderson a first- or second-round tender, though that would have increased the one-year contract Denver was offering.

Anderson earned a Pro Bowl selection following a breakout 2014 campaign in which he ran for 849 yards and eight touchdowns. The Cal product failed to meet the lofty expectations that many fans — fantasy football owners, in particular — placed on him entering the 2015 season, but he still made an impact in Denver’s backfield while sharing the workload with Ronnie Hillman.

If Anderson ends up in Miami, he’ll be joining a familiar face, as new Dolphins head coach Adam Gase was the Broncos’ offensive coordinator for the 2013 and 2014 seasons. Anderson would be asked to fill a void left by former Dolphins running back Lamar Miller, who signed with the Texans on Wednesday.

The Broncos have been dealt a couple of blows on the defensive side, losing defensive end Malik Jackson (Jacksonville Jaguars) and linebacker Danny Trevathan (Chicago Bears). Losing Anderson would be another blow to an offense currently in search of a starting quarterback.

Several other teams, including the Bears and the New England Patriots, reportedly showed interest in Anderson before he reportedly signed an offer sheet with the Dolphins.